LTC1647-3 Linear Technology, LTC1647-3 Datasheet - Page 7

• Manufacturer Part Number: LTC1647-3
• Description: Dual Hot Swap Controllers
• Manufacturer: Linear Technology

PI FU CTIO S
V
supply range for normal operation is 2.7V to 16.5V. The
supply current, I
voltage lockout (UVLO) circuit disables GATE 1 until the
supply voltage at V
2.47V). GATE 1 is held at ground potential until UVLO
deactivates. If ON1 is high and V
threshold voltage, GATE 1 is pulled high by a 10 A current
source. If V
immediately to ground. The internal reference and the
common charge pump are powered from the higher of the
two V
V
V
V
and the LTC1647-2. V
nected together.
GND: Chip Ground.
ON1: Channel 1 ON Input. The threshold at the ON1 pin is
set at 1.28V with 70mV hysteresis. If UVLO and the circuit
breaker of channel 1 are inactive, a logic high at ON1
enables the 10 A charge pump current source, pulling the
GATE 1 pin above V
GATE 1 pin is pulled to ground by a 50 A current sink.
ON1 resets channel 1’s electronic circuit breaker by pull-
ing ON1 low for greater than one t
low-to-high transition at ON1 restarts a normal GATE 1
pull-up sequence.
ON2: Channel 2 ON Input. See ON1 for functional descrip-
tion.
CC
CC1
CC2
CC1
U
: The Common Positive Supply Input for the LTC1647-1
(LTC1647-3): Channel 1 Positive Supply Input. The
(LTC1647-3): Channel 2 Positive Supply Input. See
for functional description.
CC
inputs, V
U
CC1
falls below (V
CC1
CC1
, is typically 1mA. Channel 1’s under-
CC1
CC1
U
or V
CC1
. If the ON1 pin is pulled low, the
is greater than V
CC2
and V
LKO
.
– V
CC2
CC1
RESET
LKH
is above the UVLO
are internally con-
), GATE 1 is pulled
period (50 s). A
LKO
(typically
LTC1647-1/LTC1647-2/LTC1647-3
FAULT 1: Channel 1 Open-Drain Fault Status Output.
FAULT 1 pin pulls low after 0.3 s (t
breaker measures greater than 50mV across the sense
resistor connected between V
pulls low, GATE 1 also pulls low. FAULT 1 remains low until
ON1 is pulled low for at least one t
FAULT 2: Channel 2 Open-Drain Fault Status Output. See
FAULT 1 for functional description.
SENSE 1: Channel 1 Circuit Breaker Current Sense Input.
Load current is monitored by a sense resistor connected
between V
voltage across the sense resistor exceeds 50mV (V
disable the circuit breaker, connect SENSE 1 to V
order to obtain optimum performance, use Kelvin-sense
connections between the V
current sense resistor.
SENSE 2: Channel 2 Circuit Breaker Current Sense Input.
See SENSE 1 for functional description.
GATE 1: Channel 1 N-Channel MOSFET Gate Drive Output.
An internal charge pump guarantees at least 10V of gate
drive from a 5V supply. Two Zener clamps are incorpo-
rated at the GATE 1 pin; one Zener clamps GATE 1
approximately 15V above V
clamps GATE 1 appoximately 28V above GND. The rise
time at GATE 1 is set by an external capacitor connected
between GATE 1 and GND and an internal 10 A current
source provided by the charge pump. The fall time at GATE
1 is set by the 50 A current sink if ON1 is pulled low. If the
circuit breaker is tripped or the supply voltage hits the
UVLO threshold, a 50mA current sink rapidly pulls GATE 1
low.
GATE 2: Channel 2 N-Channel MOSFET Gate Drive Output.
See GATE 1 for functional description.
NC: No Connection.
CC1
and SENSE 1. The circuit breaker trips if the
CC
CC1
CC
and SENSE pins to the
and SENSE 1. If FAULT 1
and the second Zener
RESET
FAULT
period.
) if the circuit
CB
CC1
). To
7
. In